Generally, in a photographic light-sensitive material, building, into the light-sensitive material, a photographically useful compound that is necessary for image formation, has many advantages, such as that the preparation of a development processing solution is made simple, the control of the developing solution is made easy, the composition of the developing solution changes less, and the treatment of the waste liquor is made easy. However, building, into a light-sensitive material, a photographically useful compound that is susceptible to air oxidation or hydrolysis, or that is thermally unstable, is not easy. For example, building an aromatic primary amine, which is a color-developing agent, into a light-sensitive material has many defects, such as that, for example, desensitization, fogging, or stain of the light-sensitive material occurs during its storage, and satisfactory color formation is not obtained. Therefore, building an aromatic primary amine, which is a color-developing agent, into a light-sensitive material has not yet been put into practice.
To cope with these problems, a method has been attempted so far in which a photographically useful compound is built into a light-sensitive material in the form of a protected compound that is made inactive or is relatively lowered in activity, and the built-in compound is activated by deprotecting the compound during the processing, utilizing a change in pH during the processing. However, the defect of this method is that it is difficult to control satisfactorily the difference between the activity of the protected compound and the activity of the deprotected compound; for example, the protection was too stable to be deprotected completely by a change in the processing pH, or the photographically useful compound that is an active substance was released partially under the conditions during long-term storage. Such protective groups are described, for example, in U.S. Pat. Nos. 4,690,885, 4,358,525, 4,554,243, and 5,019,492.
As techniques free from the defects described above for the deprotection of a protected photographically useful compound by a suitable method, image-forming methods in which a di-nucleophilic agent having a function for selective deprotection is added to a processing solution, are reported in U.S. Pat. No. 5,256,525 and JP-A-9-133990 ("JP-A" means unexamined published Japanese patent application). Further, as a similar technique, an image-forming method in which the selective deprotection is carried out in the presence of peroxide anions, is reported in U.S. Pat. No. 5,538,834.
In these techniques, however, although the addition of the di-nucleophilic agent or the peroxide to the processing solution accelerates the deprotection at the time of the processing, it uses a difference in the reaction rate for hydroxide ions, and the employed deprotection reaction can proceed more or less even with hydroxide ions alone. Accordingly, both the activity at the time of processing and the storage stability described above were difficult to be secured completely at the same time, and the level of securing them was still unsatisfactory.
On the other hand, that a carbonyl group is converted into a hydroxyl group in an alkaline solution via a rearrangement reaction in the presence of a peroxide, such as a peracid, is widely known as an organic synthesis reaction called the Dakin reaction or the Bayer-Villiger reaction. This reaction does not proceed at all in the absence of a peracid or a peroxide. Accordingly, it has been found that if this reaction is utilized, both the activity at the time of processing and the storage stability described above can be secured completely at the same time.
In the meantime, generally in a color photographic light-sensitive material, when the said light-sensitive material is exposed to light imagewise and then subjected to color-development, the oxidized p-phenylenediamine derivative reacts with a coupler to form an image. In this system, color reproduction by the subtractive color technique is used, and, to reproduce blue, green, and red colors, couplers that form dye images of yellow, magenta, and cyan in color, respectively complementary to blue, green, and red, are used.
Color development is attained by immersing an exposed color photographic light-sensitive material in an aqueous alkali solution containing a p-phenylenediamine derivative (color developer). However, the p-phenylenediamine derivative (a photographically useful compound) made into an aqueous alkali solution is unstable and is apt to deteriorate with time. Therefore there is no problem when the processing quantity of the color photographic light-sensitive material is large and the replenisher is frequently replenished, but when the processing quantity is small and the replenisher is less replenished, the color developer cannot withstand use for a long period of time and is required to be replaced, which is a problem.
If the p-phenylenediamine derivative in the color developer is removed from the processing solution, the above problem of deterioration with time and the complicated problem of the liquid-waste treatment of the color developer can be solved. However, when the p-phenylenediamine derivative is removed from the processing solution, color formation itself does not take place. In order to form color with an alkali solution from which the p-phenylenediamine derivative is removed (hereinafter abbreviated to an activator solution), suitably a p-phenylenediamine derivative, or a compound that can act like it, is contained in a light-sensitive material.
However, if a p-phenylenediamine derivative is contained in a light-sensitive material as it is, when the unprocessed light-sensitive material is stored for a long period of time, for example, it is oxidized with oxygen, to form stain, or it reacts with the coexistent couplers, to produce dyes, causing deterioration of images. Further, it affects the coexistent silver halide, causing image formation to fluctuate.
As a system for building in a compound other than p-phenylenediamine derivatives, there is a method in which a stable color-forming reducing agent is built into a light-sensitive material. For instance, there can be mentioned methods in which a hydrazine compound is built into a hydrophilic colloid layer, as described, for example, in EP-A-0 544 491 (A1), EP-A-565 165 (A1), JP-A-8-286340, JP-A-8-292529, JP-A-8-297354, JP-A-8-320542, and JP-A-8-292531.
As another method in which a color-developing agent is stably built into a light-sensitive material, a method is conceivable in which a p-phenylenediamine derivative in the stable form of a precursor is built into a light-sensitive material.
The precursor of a p-phenylenediamine derivative that can be built in includes compounds described in U.S. Pat. Nos. 2,507,114, 3,342,597, 4,060,418, JP-A-56-6235, JP-A-56-89735, JP-A-58-192031, JP-A-63-123046, and JP-A-6-347963. These compounds are, however, compounds that release p-phenylenediamine derivatives under alkaline conditions at the time of processing, and such compounds release p-phenylenediamine derivatives gradually, inevitably, in the presence of water or the like even during storage, leading to the same problems as when a p-phenylenediamine derivative itself is added to a light-sensitive material. It is quite difficult not to allow a p-phenylenediamine derivative to be released during storage but to allow it to be released in a short period of time only under alkaline conditions at the time of processing, and it has not yet been attained to secure both satisfactory storage stability and color-forming property at the same time. To deal with these problems, in contrast to these compounds, compounds that can release p-phenylenediamine derivatives using hydrogen peroxide are described in U.S. Pat. No. 5,538,834 and JP-A-5-257226. Indeed, in the case of these compounds, since the release reaction is accelerated with hydrogen peroxide, it is possible to increase the reaction activity at the time of processing, with storage stability retained. Even by means of these compounds, the storage stability was, however, still unsatisfactory, and there is need for development of a technique in which a p-phenylenediamine derivative (a photographically useful compound) is allowed to be contained stably during a long-term storage of the light-sensitive material, and the derivative can be released quickly at the time of processing.